TSL: Fix auto type conversion for layout parameters

[sunag]

Fixes #32034

Description

• Fix auto type conversion for layout parameters
• Improve description about isGenerateOnce

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

	Before	After	Diff
WebGL	338.24 79.14	338.24 79.14	+0 B +0 B
WebGPU	591.1 163.33	591.1 163.33	-2 B +2 B
WebGPU Nodes	589.7 163.13	589.7 163.13	-2 B +2 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

	Before	After	Diff
WebGL	469.7 113.74	469.7 113.74	+0 B +0 B
WebGPU	660.52 178.65	660.52 178.66	-2 B +2 B
WebGPU Nodes	614.53 167.84	614.53 167.84	-2 B +1 B